On Mon, 22 Sep 2003, David Brownell wrote: > > So it is somehow related to USB-1 vs USB-2. I don't understand why the > > device would make a difference for something like mode page 8, but it > > looks like it transfers data fine for _small_ mode page requests under > > USB-1, and under USB-2 it works even for big ones. > > It could be some kind of logic in the device forgetting that to use > the right maxpacket setting in that specific case.
Just a wild guess: If the device misbehaved on HS/FS transition and would send packets >64 bytes in FS mode, I think it would explain the babble issue: * the 128 byte read which reported babble was the first IN transfer >64 byte and the babble condition was reported after receiving 64 bytes, i.e. at a point where the HC has stored _less_ data than expected! * limiting the transfer length to 64 bytes made the babble disappear * works with EHCI because HS can handle bigger packets Unfortunately I don't see an easy way to check the sourced packed size on the wire - except using a bus analyzer of course. I'm not sure how uhci behaves with packets exceeding FS max packet size - if it doesn't fit into the read buffer it should report babble as well - but what if the buffer is big enough and it's just the packet is to big? IIRC the TD's actlen is 11-bit anyway. Could it be this device (mis)uses HS maxpacket when operating at fullspeed? Martin ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
